Why do SW Projects Fail?

Transcription

1 Why do SW Projects Fail? Don't do what customers want Or projects are late Or over budget Or hard to maintain and evolve Or all of the above Inspired Agile Lifecycle 1

2 Agile Lifecycle Work closely, continuously with stakeholders to develop requirements, tests Users, customers, developers, maintenance programmers, operators, project managers, Maintain working prototype while deploying new features every iteration Typically every 1 or 2 weeks Instead of 5 major phases, each months long Check with stakeholders on what s next, to validate building right thing (vs. verify) 2

3 Agile Iteration 3

4 Behavior-Driven Design (BDD) BDD asks questions about behavior of app before and during development to reduce miscommunication Requirements written down as user stories Lightweight descriptions of how app used BDD concentrates on behavior of app vs. implementation of app Test Driven Design or TDD (next chapter) tests implementation 4

5 User Stories 1-3 sentences in everyday language Fits on 3 x 5 index card Written by/with customer Connextra format: Feature name As a [kind of stakeholder], So that [I can achieve some goal], I want to [do some task] 3 phrases must be there, can be in any order Idea: user story can be formulated as acceptance test before code is written 5

6 Why 3x5 Cards? (from User Interface community) Nonthreatening => all stakeholders participate in brainstorming Easy to rearrange => all stakeholders participate in prioritization Since stories must be short, easy to change during development As often get new insights during development 6

7 Different stakeholders may describe behavior differently See which of my friends are going to a show As a theatergoer So that I can enjoy the show with my friends I want to see which of my Facebook friends are attending a given show Show patron s Facebook friends As a box office manager So that I can induce a patron to buy a ticket I want to show her which of her Facebook friends are going to a given show 7

8 Product Backlog Real systems have 100s of user stories Backlog: User Stories not yet completed (We ll see Backlog again with Pivotal Tracker) Prioritize so most valuable items highest Organize so they match SW releases over time 8

9 Which expression statement regarding BDD and user stories is FALSE? BDD is designed to help with validation (build the right thing) in addition to verification BDD should test app implementation User stories in BDD play same role as design requirements in Big Design Up Front This is a valid User Story: Search TMDb I want to search TMDb As a movie fan So that I can more easily find info 9

10 SMART stories Specific Measurable Achievable (ideally, implement in 1 iteration) Relevant ( the 5 why s ) Timeboxed (know when to give up) 10

11 Specific & Measurable Each scenario testable Implies known good input and expected results exist Anti-example: UI should be user-friendly Example: Given/When/Then. 1.Given some specific starting condition(s), 2.When I do X, 3.Then one or more specific thing(s) should happen 11

12 Achievable Complete in 1 iteration If can t deliver feature in 1iteration, deliver subset of stories Always aim for working end of iteration 12

13 Timeboxed Estimate what s achievable using velocity Each story assigned points (1-3) based on difficulty Velocity = Points completed / iteration Use measured velocity to plan future iterations & adjust points per story Pivotal Tracker (later) tracks velocity 13

14 Relevant: business value Ask Why? recursively until discover business value, or kill the story: Protect revenue Increase revenue Manage cost Increase brand value Making the product remarkable Providing more value to your customers has a good example 14

15 Stories are SMART but features should be relevant Specific & Measurable: can I test it? Achievable? / Timeboxed? Relevant? use the 5 whys Show patron s Facebook friends As a box office manager So that I can induce a patron to buy a ticket I want to show her which Facebook friends are going to a given show 15

16 Which feature below is LEAST SMART? User can search for a movie by title Rotten Potatoes should have good response time When adding a movie, 99% of Add Movie pages should appear within 3 seconds As a customer, I want to see the top 10 movies sold, listed by price, so that I can buy the cheapest ones first 16

17 Cucumber: Big Idea Tests from customer-friendly user stories Acceptance: ensure satisfied customer Integration: ensure interfaces between modules consistent assumptions, communicate correctly. Cucumber meets halfway between customer and developer User stories don't look like code, so clear to customer and can be used to reach agreement Also aren't completely freeform, so can connect to real tests 17

18 Example User Story Feature: User can manually add movie 1 Feature Scenario: Add a movie 1 Scenarios / Feature Given I am on the RottenPotatoes home page When I follow "Add new movie" Then I should be on the Create New Movie page When I fill in "Title" with "Men In Black" And I select "PG-13" from "Rating" And I press "Save Changes" Then I should be on the RottenPotatoes home page And I should see "Men In Black" 3 to 8 Steps / Scenario 18

19 Cucumber User Story, Feature, and Steps User story: refers to a single feature Feature: 1 or more scenarios that show different ways a feature is used Keywords Feature and Scenario identify the respective components Scenario: 3 to 8 steps that describe scenario Step definitions: Ruby code that tests steps Usually many steps per step definition 19

20 5 Step Keywords 1. Given steps represent the state of the world before an event: preconditions 2. When steps represent the event (e.g., push a button) 3. Then steps represent the expected outcomes; check if its true 4. / 5. And and But extend the previous step 20

21 Steps, Step Definitions, and Regular Expressions User stories kept in one set of files: steps Separate set of files has Ruby code that tests steps: step definitions Step definitions are like method definitions, steps of scenarios are like method calls How match steps with step definitions? Regexes to match the English phrases in steps of scenarios to step definitions! Given /^(?: {}I )am on (.+)\$/ I am on the Rotten Potatoes home page 21

22 Red-Yellow-Green Analysis Cucumber colors steps Green for passing for not yet implemented Red for failing (then following steps are Blue) Goal: Make all steps green for pass (Hence green vegetable for name of tool) 22

23 Capybara Need tool to act like user that pretends to be user follow scenarios of user story Capybara simulates browser Can interact with app to receive pages Parse the HTML Submit forms as a user would Cannot handle JavaScript Other tool (Webdriver) can handle JS, but it runs a lot slower, won t need yet 23

24 Demo Add feature to cover existing functionality Note: This example is doing it in wrong order should write tests first Just done for pedagogic reasons (Or can look at screencast: 24

25 Which is FALSE about Cucumber and Capybara? Cucumber and Capybara can perform acceptance and integration tests A Feature has 1 User Stories, which are composed typically of 3 to 8 Steps Steps use Given for current state, When for action, and Then for consequences of action Cucumber matches step definitions to scenario steps using regexes, and Capybara pretends to be user that interacts with SaaS app accordingly 25

26 SaaS User Interface Design SaaS apps often faces users User stories need User Interface (UI) Want all stakeholders involved in UI design Don t want UI rejected! Need UI equivalent of 3x5 cards Sketches: pen and paper drawings or Lo-Fi UI 26

27 Lo-Fi UI Example (Figure 4.3, Engineering Long Lasting Software by Armando Fox and David Patterson, Alpha edition, 2012.) 27

28 Storyboards Need to show how UI changes based on user actions HCI => storyboards Like scenes in a movie But not linear 28

29 Example Storyboard (Figure 4.4, Engineering Long Lasting Software by Armando Fox and David Patterson, Alpha edition, 2012.) 29

30 Lo-Fi to HTML Tedious to do sketches and storyboards, but easier than producing HTML! Also less intimidating to nontechnical stakeholders => More likely to suggest changes to UI if not code behind it More likely to be happy with ultimate UI Next steps: CSS (Cascading Style Sheets) and Haml Make it pretty after it works 30

31 Which is FALSE about Lo-Fi UI? Like 3x5 cards, sketches and storyboards are more likely to involve all stakeholders vs. code The purpose of the Lo-Fi UI approach is to debug the UI before you program it SaaS apps usually have a user interfaces associated with the user stories While it takes more time than building a prototype UI in CSS and Haml, the Lo-Fi approach is more likely to lead to a UI that customers like 31

32 And in Conclusion Debugging: Read, Ask, Search, Post Rails Pitfalls: Too much code in Controller, Some extra code in View Agile prototypes, iterate with customer BDD Design of app before implementation User Story all stakeholders write what features want on 3x5 cards Cucumber magically turns 3x5 card user stories into acceptance tests for app 32